Canonical partition function for N ideal gasses

[Schwarzschild90]

Homework Statement

Exercise 4 in the upload titled Dok1.pdf.

Write down an expression for the canonical partition function for N ideal Na2 gas molecules, when the rotational contribution is treated classically, and all inner degrees of freedom are treated quantum mechanically. Use this and earlier results to calculate an expression for the equilibrium constant for the reaction (1) and calculate its value at =1000.

Homework Equations

and 3. the attempt at a solution[/B]
A tutor came up with this nonsensical solution:

 

[Schwarzschild90]

I've redone the exercise and come up with the following solution instead: